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NPT Spec Table
NPT KS Specifications — 10 sizes
ASME B1.20.1
ANSINPT
10 sizes| Nominal NPS | TPI | OD (mm) | Pitch Dia (mm) | Taper | Standard |
|---|---|---|---|---|---|
| 1/16 | 27 | 7.938 | 6.888 | 1:16 | ASME B1.20.1 |
| 1/8 | 27 | 10.287 | 9.233 | 1:16 | ASME B1.20.1 |
| 1/4 | 18 | 13.716 | 12.126 | 1:16 | ASME B1.20.1 |
| 3/8 | 18 | 17.145 | 15.545 | 1:16 | ASME B1.20.1 |
| 1/2 | 14 | 21.336 | 19.264 | 1:16 | ASME B1.20.1 |
| 3/4 | 14 | 26.67 | 24.579 | 1:16 | ASME B1.20.1 |
| 1 | 11.5 | 33.401 | 30.826 | 1:16 | ASME B1.20.1 |
| 1 1/4 | 11.5 | 42.164 | 39.551 | 1:16 | ASME B1.20.1 |
| 1 1/2 | 11.5 | 48.26 | 45.621 | 1:16 | ASME B1.20.1 |
| 2 | 11.5 | 60.325 | 57.633 | 1:16 | ASME B1.20.1 |
This specification follows ANSI/ASME (American National Standards). Inch-based units apply; required for maintaining US/Canadian equipment and meeting North American market requirements.
NPT (National Pipe Taper) is the US standard tapered pipe thread per ASME B1.20.1, with a 1:16 taper (half-angle 1.7899°). The taper creates metal-to-metal wedging and friction at makeup, providing pressure-tight sealing. This table covers nominal pipe sizes 1/16" through 2" with OD, TPI, and pitch diameter. Widely used for low-pressure fluid, pneumatic piping, fittings, and valve connections — PTFE tape or thread sealant is required in practice.